1. Field of the Invention
The present invention relates to polypropylene resin compositions and molded articles made therefrom.
2. Description of the Related Art
Polypropylene resin compositions are materials excellent in rigidity, impact resistance, and the like, and they are used in a wide variety of applications in the form of molded articles such as automotive interior or exterior components and housings of electric appliances.
For example, JP-A5-51498 discloses a thermoplastic resin composition comprising from 50 to 750 by weight of a crystalline polypropylene, from 15 to 35% by weight of an ethylene-butene-1 copolymer rubber having a butene-1 content, an intrinsic viscosity and a Mooney viscosity each within specific ranges, and from 5 to 20% by weight of talc having an average particle diameter within a specific range.
JP-A 7-157626 discloses a thermoplastic resin composition comprising a propylene-ethylene block copolymer prepared by multistage polymerization and a polyolefin rubber. This document teaches to use, as the propylene-ethylene block copolymer, a block copolymer composed of a block copolymer including a propylene-ethylene random copolymer phase having an ethylene content of from 5 to 50% by weight and an intrinsic viscosity of from 4.0 to 8.0 dl/g and a block copolymer including a propylene-ethylene block copolymer phase having an ethylene content of more than 50% by weight but not more than 98% by weight and an intrinsic viscosity of not less than 2.0 dl/g but less than 4.0 dl/g.
JP-A 9-157492 discloses a thermoplastic resin composition comprising a propylene-ethylene block copolymer prepared by multistage polymerization, an ethylene-butene copolymer rubber and talc. This document teaches to use, as the propylene-ethylene block copolymer, a block copolymer composed of a homopolypropylene portion whose melt flow rate is within a specific range and whose heat of fusion determined by DSC and melt flow rate satisfy a specific relationship, a propylene-ethylene copolymer portion having a lower ethylene content and a propylene-ethylene copolymer portion having a higher ethylene content.
However, polypropylene resin compositions and molded articles produced therefrom have been requested to be improved in flow mark appearance, toughness, low temperature impact strength, especially high-speed impact strength, and balance between rigidity and surface hardness.